Description: This patch adds a set-flags ioctl, allowing various option
flags to be set on an nbd device. This allows the nbd-client to set
the device flags (to enable read-only mode, or enable discard support, etc.).
Flags are typically specified by the nbd-server. During the negotiation phase
of the nbd connection, the server sends its flags to the client. The
client then uses NBD_SET_FLAGS to inform the kernel of the options.
Also included is a one-line fix to debug output for the set-timeout ioctl.
Signed-off-by: Paul Clements <[email protected]>
---
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index d07c9f7..c544bb4 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -78,6 +78,8 @@ static const char *ioctl_cmd_to_ascii(int cmd)
case NBD_SET_SOCK: return "set-sock";
case NBD_SET_BLKSIZE: return "set-blksize";
case NBD_SET_SIZE: return "set-size";
+ case NBD_SET_TIMEOUT: return "set-timeout";
+ case NBD_SET_FLAGS: return "set-flags";
case NBD_DO_IT: return "do-it";
case NBD_CLEAR_SOCK: return "clear-sock";
case NBD_CLEAR_QUE: return "clear-que";
@@ -460,7 +462,7 @@ static void nbd_handle_req(struct nbd_device *nbd, struct request *req)
nbd_cmd(req) = NBD_CMD_READ;
if (rq_data_dir(req) == WRITE) {
nbd_cmd(req) = NBD_CMD_WRITE;
- if (nbd->flags & NBD_READ_ONLY) {
+ if (nbd->flags & NBD_FLAG_READ_ONLY) {
dev_err(disk_to_dev(nbd->disk),
"Write on read-only\n");
goto error_out;
@@ -642,6 +644,10 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
nbd->xmit_timeout = arg * HZ;
return 0;
+ case NBD_SET_FLAGS:
+ nbd->flags = arg;
+ return 0;
+
case NBD_SET_SIZE_BLOCKS:
nbd->bytesize = ((u64) arg) * nbd->blksize;
bdev->bd_inode->i_size = nbd->bytesize;
diff --git a/include/linux/nbd.h b/include/linux/nbd.h
index d146ca1..bb349be 100644
--- a/include/linux/nbd.h
+++ b/include/linux/nbd.h
@@ -27,6 +27,7 @@
#define NBD_SET_SIZE_BLOCKS _IO( 0xab, 7 )
#define NBD_DISCONNECT _IO( 0xab, 8 )
#define NBD_SET_TIMEOUT _IO( 0xab, 9 )
+#define NBD_SET_FLAGS _IO( 0xab, 10)
enum {
NBD_CMD_READ = 0,
@@ -34,6 +35,10 @@ enum {
NBD_CMD_DISC = 2
};
+/* values for flags field */
+#define NBD_FLAG_HAS_FLAGS (1 << 0) /* nbd-server supports flags */
+#define NBD_FLAG_READ_ONLY (1 << 1) /* device is read-only */
+
#define nbd_cmd(req) ((req)->cmd[0])
/* userspace doesn't need the nbd_device structure */
@@ -42,10 +47,6 @@ enum {
#include <linux/wait.h>
#include <linux/mutex.h>
-/* values for flags field */
-#define NBD_READ_ONLY 0x0001
-#define NBD_WRITE_NOCHK 0x0002
-
struct request;
struct nbd_device {